Extrusion



Jan. 2, 1945. c, McFADDEN 2,366,344

" I EXTRUSICN Filed Oct. 21, 1940 5 INVENTOR fiefzjczmirz C/VcFadden ATTORNEY Patented ion. 2, 1945 2,3 A

EXTBUSION Benjamin C. McFadden, Pittsburgh, Pa., assignor to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application October 21, 1940, Serial No. 362,047

. 5 Claims. (Cl. 207-17) The present invention relates in general to imed shape; and to the general design of the port- 'provements in the art of extrusion. It is parhole extrusion dies, including the cross-sectional ticularly directed to improvements in extrusion area and shape of the metal-flow passages die or tool structures for the production of exthrough the front die, or male member, of a. porttruded shapes or sections from unperforated bil- 5 hole type extrusion die. Of these variables, the lets or metal charges. latter is usually the only factor over which a tool Extrusion dies or tools, generally known as designer or operator has any control for any "porthole type dies, are experiencing increasing given extruded shape or section. success and acceptance in the extrusion art as Investigation of commercially known types of the development of this art is presently considporthole extrusion dies has shown that these dies ered. Such porthole die assemblies or structures in general can only be employed in extrusion opnormally comprise a front male or mandrel die erations where the extrusion pressures adjacent and a back female or exterior contour-controlling the dies are maintained at substantially 100,000 die, so arranged in assembled relationship that pounds per square inch, or under. In fact, maxithe metal of an unperforated billet, or solid metal mum pressure of 100,000 pounds per square inch charge, divides itself under the influence of presh only been p s i le f win pr l n ed exsure into one or more streams of metal which flow perience in tool design, with particular signifithrough the front die and around the mandrel cance being attached to the selection and diswhere it coalesces in a mixing or welding champosition of the metal-flow passages through the her adjacent the entrance to a die aperture in front or male die to minimize losses resulting theback die. Continued extrusion pressure causes from frictional resistance, and to reduce to a the metal to be forced out of the mixing or weldminimum abrupt c a in direction of mm of ing chamber. and to be extruded through a die the metal through such dies. orifice, which is defined between the aperture in n in their present state of developmen the female di and th mandr l, It ill be apporthole extrusion die assemblies constructed preciated that extrusiondie assemblies of this o available metals a ys exhibit an ingeneral type have eliminated the necessity of herent tendency t e d u der the influence of using perforated or hollow metal billets in the t Pressures p rienced in extrusion P ti eproduction of tubular shapes by an extrusion h in part, is caused by the fact that it has process, and for this reason porthole type die asalways been considered desirable to maintain the semblies have found ready acceptance in the front or male die member at a minimum thickextrusion art. ness in order that frictional resistance to metal Regardless of the fact that porthole type exo g through the Ports metal-150W P ag s trusion die assemblies have experienced favorable would be reduced to a minimum. This feature acceptance in the extrusion art, these dies have of design est y educes the available seccertain inherent structural limitations which contional modulus of the front die in resistance to tribute largely to the development of excessive ben a as a result of this condition, use Of pressures during their use, which pressures often Such porthole dies is known Often result n result in considerable die breakage with attendant the production of commercially unacceptable exhigh operating maintenance. The pressures ex- 40 truded products. For example, uncontrollable perienced differ for different metals and alloys bending of the front die member, which in reality being extruded, and are particularly noticeable is composed of a plurality of bridge members at the beginning of an extrusion operation, as supporting amandrel, causes the mandrel to shift distinguished from the pressures developed after out of proper alignment with its complementary the metal of a billet has commenced to flow under female die aperture, with the result that a nonthe continued applied extrusion force. It would uniform extruded product is produced. In the probably be inaccurate to attempt to explain all case of circular tubing, this would result in the of the factors contributing to the excessive presproduction of commercially unacceptable eccensures that are developed during an extrusion optric tubing. Excessive bending also causes pereration through a porthole type extrusion die manent deformation of the male die member with assembly, but it can be definitely stated that the numerous detrimental results from its continued intensities of the developed pressures bear a defluse. In extreme cases of bending, the front die nite relationship to the ratio of the perimeter of is fractured and must be replaced. an extruded shape or section to its metal volume; It has been found that porthole extrusion dies to non-symmetry of configuration of the extrud- 5s incorporating all of the advantages of presently used dies of this type can be greatly improved by constructing the front or male die member in the form of a laminated structure wherein materials exhibiting different physical characteristic can be employed to greatly alleviate, and in some instances completely eliminate, the disadvantages arising out of bending stresses. In this connection, it has been discovered that a materially stronger and more ductile bridge construction can be developed in a male die member by It is an object of the present invention to pro-,

vide a porthole type of die assembly which has all of the advantages of present dies of this general class, but which also incorporates improved and superior features of construction.

A further object of the invention is to provide a porthole extrusion die of sturdy and rigid construction which incorporates metals or metal alloys disposed in selective relationship to their physica1 characteristics in such a manner that stressed conditions in the die structure are adequately provided for.

Another object of the invention is to provide a porthole extrusion die assembly of laminar construction which facilitates varying degrees and types of heat-treatment of the various parts of the die assembly with minimum residual hardening strains.

A further object of the invention is to provide a porthole extrusion die assembly of laminar construction which provides for interchangeability and substitution of one or more of the parts of the die structure as may be required.

Other objects and advantages of the invention will be apparent on consideration of the following description'of a specific embodiment of the present invention when taken in conjunction with the drawing forming a part hereof, in which:

Fig. 1 represents a sectional elevation taken along the line I-I of Fig. 2, and disclosing an extrusion die assembly incorporating the novel features of the present invention in association with fragmentary portions of a cooperating extrusion billet cylinder and ram;

, Fig. 2 represents an end elevation of the front die as viewed in the direction of the arrows II--II in Fig. 1;

Fig. 3 represents an end elevation as viewed from the right of Fig. 1;

Fig. 4 represents a view, in partial section, taken in the direction of the arrows IV-IV on Fig. 1;

Fig. 5 represents a fragmentary sectional view taken along the line V-V of Fig. 2; and

Fig. 6 represents a perspective view of the mandrel element removed from its supporting die structure.

Referring to the drawing, which has been selected for purposes of illustrating a porthole type extrusion die assembly embodying the prin-' ciples of the present invention, it will be seen that the general type of extrusion assembly best adapted to a realization of the features and adcoalescing chamber 24 preferably formed in the front mandrel or male die member, identified in its entirety by the reference numeral Ill, and a back female or exterior contour-controlling die.

the extrusion tools with the cylinder l4 and a ram IS, the latter being provided for the purpose of exerting the necessary pressure for extruding a billet (not shown) through the extrusion die.

0n reference to Fig. 1, it will be seen that the front or male die M is of laminar construction. three laminae having been selected for purposes of illustration. In its specific construction the die |0 is composed of three laminae l6, H, and I8 of plate-like form arranged coaxially in faceto-face relation and suitably secured to form a unitary laminated block structure. In its preferred construction, cap screws 20, extending through sleeves 2|, accurately align and secure the laminae in rigid assembled relationship.

Portholes or metal-flow passages 22 normally extend through the entire depth of the male die l0, and on assembly of the dies l0 and I2, passages 22f terminate in a mixing, welding or female die l2.

A mandrelmember 25 is supported and carried by the male die l0. In its preferred construction the mandrel 25 is provided with an enlarged head 26 which is adapted to be'received within a cavity 21 formed in the intermediate laminar section II. The mandrel 25, as illustrated in the drawing, is substantially T-shaped, the head being substantially rectangular in form, as is the shank 28, which extends through a suitable aperture in laminar section It.

The unsupported end II of the mandrel 25 is suitably formed, as by a machining operation, to represent the desired interior contour of the tubular extruded shape to be produced. This end portion 30 extends into a die aperture 32 in the female die |2, the mandrel tip 30 and die aperture 32 cooperating to form a die orifice of the exact cross-section of the extruded shape to be fabricated.

vantages of the present invention comprises a 5 In the adaptation and operation of the extrusion tools of this invention, a mandrel of desired configuration is inserted through the aperture provided in lamina ll in such a manner that the shoulder 36 formed at the jointure of head 26 and shank 28 prevents movement of the mandrel 25 through this section of the die structure. Laminar section II is thereafter placed in abutting relationship with section ill with its aperture 21 in registry with the mandrel head 28. Sleeves 2| are then placed within aligned apertures disposed in sections l1 and I8, and laminar section I6 is [thereafter positioned in abutting relationship with section II, whereby complementary apertures in the section It regand the equalization and distribution of pressure in the extrusion die as a result of the size and cross-sectional area of the shape to be extruded. The front or male die I having been assembled as aforedescribed, it is now necessary to properly register this die with its cooperating female die l2. This is normally accomplished through the medium of dowel pins 34 which are preferably secured in the female die l2 in registry with apertures in laminar section l8 of male die 10. An assembled die structure, preferably in axial alignment and cooperation with the billet cylinder I4 and ram I5, may now be employed to perform an extrusion operation, whereby the metal or material of a billet charged within cylinder I may be forced through the assembled porthole extrusion die. It will be apparent that it will be necessary to provide those known elements of an extrusion mechanism necessary for maintaining dies l0 and 12 in pressure-resistant relationship with respect to the extrusion pressure employed during an extrusion operation.

The individual laminae of male die permit selection of materials from which the same may be constructed to obtain maximum resistance to bending stresses developed during the use of the die assembly of this invention. For example, each laminar section may comprise the same, or an entirely distinctive material; and further, each may be separately heat-treated to develop predetermined physical properties therein. The same remarks apply with respect to the mandrel 25, and by proper selection of the materials from which the laminae l6, l1, and iii are constructed, and by employing a separate mandrel 25, it will be manifest that, through proper heat-treatment of these various elements, a front mandrel type porthole extrusion die may be constructed which will provide optimum strength and physical properties in direct resistance to the forces exerted on a die of this type during an extrusion operation. Manifestly, any one portion or lamina of the die Ill may be thermally treated without in any way influencing the particular treatment required for an adjacent portion of the die, including the mandrel 25. It will be further understood that the laminar structure, even whereall of the laminations are composed of the same material, permits development of heat-treated properties which could not be obtained in the heattreatment of a solid die member of the same material.

A further advantage attributable to the laminar construction incorporated in the die ll] of this invention lies in the fact that the machining operations necessary in the production of the die have been greatly simplified. For example, each lamina may be separately machined and there after assembled in proper registry with its adjacent and coperating lamina. The sectional laminar construction further permits the substitution of various types of mandrels without the necessity of constructing an entirely new male die member. It is also inherent in laminar die structures of the type herein described, to select the materials from which the individual laminae and mandrel are constructed in relation to their heat transfer characteristics, whereby the laminae and mandrel may be assembled to best advantage to relieve localized heating within the die structures of this invention.

Although a specific die structure has been selected for purposes of illustrating and describing the present invention, it is to be understood that the specific embodiment hereinabove illustrated and described is not to be interpreted as limiting the scope of the present invention, except as defined in the claims appended hereto.

What is claimed is:

1. An extrusion tool assembly comprising a front die member and a back die member, said front die member comprising a plurality of laminar sections arranged in parallel abutting relationship, at least one metal-flow passage through said front die, a mandrel replaceably supported within the laminar sections, removable means for securing the laminar sections and mandrel in rigid assembled relationship, an aperture in said back die, said front and back dies being assembled to present the mandrel in cooperative relationship with the die aperture to define a die orifice therebetween,'and said laminar sections being selected and disposed in predetermined relationship to present definite physical properties in resistance to bending stresses developed in the extrusion tool assembly during its use.

2. In a porthole type extrusion die, a front die member composed of a plurality of laminae arranged in abutting relationship, a T-shaped mandrel member associated with said front die member, said mandrel being disposed with its shank extending outwardly through an aperture in one lamina, the head of said mandrel being retentively disposed in a cavity in an adfacent lamina, and said mandrel and laminae being selected from materials having physical properties proportionate to the stresses developed in the die structure during its use.

3. In a porthole type extrusion die, a front die member composed of a plurality of lamin'ae arranged in parallel abutting relationship, a plurality of sets of apertures extending through said laminae, each set of apertures being in registration, sleeves within said registered apertures, headed bolts extending through said sleeves in threaded engagement with an extreme end lamina, the heads of said bolts being in clamping relationship with the other end lamina, at least one metal-flow passage extending through said laminae, and a mandrel having a portion extending forwardly of an end lamina and another portion extending into the laminated structure where it is positively and replaceably secured.

4. In a porthole type extrusion die for the extrusion of unpierced billets, a front die therefor comprising a plurality of plate-like laminations of substantially identical form assembled in coaxial, face-to-face abutting relation, means carried by said laminations for clamping them in said relationship to form a unitary structure, a metal fiow passage through said unitary structure formed by aligned openings in said laminae, and a mandrel of rectangular cross section disposed within and supported by said assembled laminations and extending only at one end past the rear face thereof to form a male die defining the interior configuration of a shape to be extruded when said front die is associated with a back die, said mandrel being removable for replacement upon disassembly of said laminations.

5. In a porthole type extrusion die for the extrusion of unpierced billets, a front die therefor comprising a plurality of plate-like laminations of substantially identical form assembled in coaxial, face-to-face abutting relation, means for clamping said laminations in said relationship to form a unitary structure, a metal flow passage through said unitary structure formed by aligned openings in said laminae, and a headed mandrel disposed entirely within and rigidly supported by said assembled laminations and having a shank portion extending rearwardly past the rear face thereof to form a male die defining the interior configuration of a shape to be extruded when said sistance to bending stresses developed in said structure during its use without increasing the thickness of said laminations.

BENJAMIN C. MOFADDEN. 

